The guys at my plastic supplier talked me out of switching from acrylic to polycarb because it's softer than acrylic and more prone to warping due to gravity. 
Acrylic Fabrication Q & A
- Thread starter Turbo's Aquatics
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reef4Tom
Community Member
I was curious if any of you are doing display tanks? I watched a start-to-finish how to on youtube and I have to say, I was very impressed. This guy did not use the pin method.
What are your experiences with DT's good or bad.
Thanks.
What are your experiences with DT's good or bad.
Thanks.
Lowell Lemon
2500 Club Member
How big of a display tank are you looking for? My liability insurance is still active and I have built thousands of tanks since 1981. I am currrently looking for a source in the Northwest for PolyCast Acrylic to start up a new line of tanks.
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My Tank Thread
I suggested @reef4Tom post here for advice on building his own acrylic tank. He made a post in the DIY thread: https://www.reef2reef.com/threads/diy-acrylic-tank-large-100-gallons.244122/ and I directed him to this thread for some solid advice from the participants. He made reference to watching a video series that after reading and participating in this thread I thought maybe he could get some good direction.
reef4Tom
Community Member
Lowell, I currently have a 75 gallon glass, with a HOB fuge/skimmer combo (it works, but not great). I eventually want to upgrade to a 120 gallon, with a sump/fuge. I've looked at buying an acrylic tank, but the price tag has kept me far away. I'm not in any kind of hurry, just doing my research ahead of time. I appreciate your reply.
Shawn
Tango2
Active Member
I'm on my next step in my build, and wanted to get advice on how to best setup for the next seam.
Below is my progress so far:
Right side in picture will be sump front, and I now need to weld the rear panel, which will have to be horizontal for gluing. Should I just build a quick support for the weight of the baffles in addition to my right angle jig for the joint itself?
Also, my joints were not completely smooth, which was causing my bubbles previously.
Below is my progress so far:
Right side in picture will be sump front, and I now need to weld the rear panel, which will have to be horizontal for gluing. Should I just build a quick support for the weight of the baffles in addition to my right angle jig for the joint itself?
Also, my joints were not completely smooth, which was causing my bubbles previously.
reef4Tom
Community Member
I don't disagree. I see things all the time on youtube, that make me say "I can do that" only to find out it's not always that easy.
OP
OP
Yes, for that order of bonding that is what you will need to do. It's hindsight, but this could have been avoided if you made the "front" (right) panel bond to the side panel (with the notches in it) because then both the front and back panels would technically be "end" panels, so the whole thing could be laying on the notched panel with all the baffles sitting on top.
As it stand now, you would bond the rear (left) panel on and you would have to build supports to make sure the weight of the baffles and front panel don't tilt the whole assembly out of position, while also making sure that the alignment of the end of that rear panel is perfect and the distance is just right so that you can bond the last panel in place. That is going to be very tricky, but acrylic is somewhat forgiving, meaning you can use clamps and such to force the alignment if you don't get it perfect, then use lots of weights on top of that assembly. I would recommend, after bonding the left/rear panel on (the next panel) that you let it sit and cure for 48 hours to make sure that when (if) you have to force the panels into alignment, that most recent joint is well cured so that it doesn't try to pull the seam apart.
Once you get the last panel in place and bonded, same thing. Wait 48 hours before doing any trim routing prior to putting the bottom panel on. I choose not to do the trim routing until all panels are installed, this helps with the corners a bit. Having your excess hanging out there gives the solvent a little extra area to bond, and if air creeps in then it's usually in the area you are trimming off, not the finished (trimmed) corner. Your only remedy to that situation is to round off all the corners after everything is cured, which works usually as the air creep on a outer corner to bottom bond is usually right in the very corner. As long as your material is thick enough (which yours looks like it is - 1/2"?)
Tango2
Active Member
My material is 3/8, and I understand what you are saying about the bonding order. If you look at my design (which I think I posted here, if not its in my sump build thread) there is a fuge on the other side of that notched panel. The excess on the right and left side in the picture is actually the front and back of the fuge. I couldn't figure out an easier order or method to weld the panels together with this design.
Tango2
Active Member
I figured out a pretty simple jig that so far seems to be working great. Finished the weld up about an hour ago - so far so good. Just notched a scrap piece of 3/4" plywood. Worked like a champ!
Tango2
Active Member
I'm gluing my last side on my sump, and I have between 1/16" and 1/8" gap between one of the baffles and the side. Everything else is flush. Will Weldon 16 do the trick to fill this void, or should I take a different approach?
OP
OP
WO16 is not a gap filler, at least not for really large gaps, it s really kind of junk. It dries to a thin profile, similar to WO4 or WO3, it's just in a thicker form. It's really not good for structural bonds.
What you can do, easily (but it looks ugly) is take a 1" wide strip of acrylic, and bond it to the loose baffle such that this additional strip makes full contact with the intended panel, then bond to the panel. Actually, it's better to bond that strip to the intended panel, then bond the baffle to the strip. Then you can do layers of WO16 if you still have leaking along the joint.
What you can do, easily (but it looks ugly) is take a 1" wide strip of acrylic, and bond it to the loose baffle such that this additional strip makes full contact with the intended panel, then bond to the panel. Actually, it's better to bond that strip to the intended panel, then bond the baffle to the strip. Then you can do layers of WO16 if you still have leaking along the joint.
Tango2
Active Member
I was able to do some light sanding, shimming, and creative clamping and got everything lined up nice. I ended up with a really nice weld.
Because the baffles were my "high point", I attached them first. The back went next, and was pretty uneventful as well. The front was another story.
In the end, it took 2 pipe clamps, numerous wedges, a ratchet clamp and a 2x4 to get everything lined up halfway close. So far so good. I'll pull the clamps in the morning and assess the overall assembly. Couldn't have done it without this thread.
I'd like to add one piece of advice. I found that the bondo spreaders that you find in the automotive section or an automotive paint shop work really well as shims.
Because the baffles were my "high point", I attached them first. The back went next, and was pretty uneventful as well. The front was another story.
In the end, it took 2 pipe clamps, numerous wedges, a ratchet clamp and a 2x4 to get everything lined up halfway close. So far so good. I'll pull the clamps in the morning and assess the overall assembly. Couldn't have done it without this thread.
I'd like to add one piece of advice. I found that the bondo spreaders that you find in the automotive section or an automotive paint shop work really well as shims.
Triton Marine
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We build sumps here and was wondering what solvent you all have been using? We use different types for what we are using it for. Just trying to see if there is one product line you all prefer?
Drauka99
Active Member
After discovering silicone on the inside where the previous owner apparently thought to use that to fix the leak, I disassembled the whole thing and cut out the crack that you guys saw. Have the edges sanded with 60 and 120 grit sandpaper. A few more passes with some finer grit sandpaper and me and the local who has done this stuff before will attempt a rebuild.
Also allowed me to make it a bit smaller to fit my sump area better and I can now add some float switch brackets inside for apex ato control.
Lowell Lemon
2500 Club Member
Most of us mix our own formula. Look back on this thread for a response to that question by Floyd R Turbo. I stopped using packaged solvent years ago due to low bond strength. The lowest bond strength was with Weldon 40 and 42 in our tests. Methylene Chloride with a 2%-5% addition of Glacial Acetic Acid is the best mix. You increase the Acetic Acid due to humidity to prevent blushing (white residue) around the bond area. These chemicals are known Carcinogens so read the MSDS and prevent contact with your skin as it passes the skin barrier easily. Ventilation in the fabrication area is a good idea as well. The vapors are heavier than air and should be avoided when breathing.
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